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,1,1 r i 

RITCHIE'S 



ILLUSTRATED CATALOGUE 



OF 



SCHOOL APPARATUS. 



£ 



BOSTON: J 

150 TREMONT STREET. 

187 3. 




RITCHIE'S ROTARY AIR PUMP. 



Entered, according to Act of Congress, in the year 1871, 

By B. S. RITCHIE & SONS, 

In the Office of the Librarian of Congress, at Washington. 

Entered, according to Act of Congress, in the year 1873, 

By E. S. RITCHIE & SONS, 

In the Office of the Librarian of Congress, at Washington. 



Rand, Avery, & Co., Printers. 



Advertisement. 



Terms, Cash. No discount or deviation can bo made 
from Catalogue prices ; and those who favor us with or- 
ders by mail may rely on receiving instruments as good 
in quality, and at the same price, as if they came per- 
sonally. 

Orders can be made by simply giving the numbers, 
with prices and date of Catalogue. 

Drafts at sight, to our order, on New York or Philadel- 
phia, received at par ; for small sums, post-office money 
orders are convenient. 

A charge of two and a half per cent, for packing and 
delivery at railroad station will be made. 

Great care will be used in packing; but unless Ave 
insure, our responsibility must end with delivery in good 
order to the public carrier. Our charge for insurance 
against loss and breakage is 2J per cent. 

We would draw attention to the Sets, which have been 
carefully selected, and to the favorable conditions on 
which these will be sent, given on page 35. 

Purchasers are desired to give particular directions 
by what Lines and route to forward. 

For testimonials from the highest sources, we refer to 
letters at the close of Catalogue. 



RITCHIE'S CATALOGUE OF 

\ i 1 b a jr jj 1 1 k I Instrument* 

WILL BE SENT ON APPLICATION". 



PREFACE 



The following Catalogue has been prepared of Appa- 
ratus especially adapted for the requirements of the Gram- 
mar and High Schools of the country. It has chiefly 
been compiled from our Catalogue of Philosophical In- 
struments, with some new instruments which we have 
devised and constructed for the purpose. 

The aim has been to select articles that each will illus- 
trate a Principle in the simplest and clearest manner ; to 
adopt the size best uniting efficiency with economy ; to 
avoid multiplying experiments illustrating the same prin- 
ciple ; and to omit such as are beyond the intended 
range. 

The instruments enumerated in this Catalogue are 
almost exclusively of our own manufacture. We shall 
adhere strictly to our rule, that everything shall be thor- 
oughly well made and finished, of best materials, and 
carefully adjusted ; and every article is warranted to be 
so, and to correspond to the description. 

Particular care is given to the lacquering, which is 
done in a manner that will resist the action of the atmos- 
phere, and bear use and handling for a long time untar- 
nished. 

E. S. RITCHIE & SONS. 

Edward S. Ritchie. 
Thomas I*. Ritchie. 
John Ritchie. 
Andricw M. Ritchie.- 

(iv) 



RITCHIE'S 



CA-TA^OGTCTE 



SCHOOL APPARATUS 



LAWS OF MATTER AND MECHANIC! 





No. l. 



No. 2. 







No. 3. 



No. 7. 



No. 8. 



Price. 

Adhesion Plates; a pair of ground glass plates, with handles, $1.25 

Lead Hemispheres, for adhesion. Scrape the surfaces bright, and press 

them firmly together, at the same time moving one slightly on the other, 1.25 

Inertia Apparatus ; stand, with spring and ball, 1.75 

Capillary Tubes ; a set of six glass tubes of different calibre, in a box, . . .75 
Capillary Tubes; six tubes sealed into a bar to rest upon a tumbler, . . 1.50 
Capillary Plates ; of plate glass with wood clamps. Separate them at one 

edge slightly, and set them upright in a plate of water, 1 .50 

Collision Balls ; a base and pillar, with a frame sustaining five lignum-vitae 

balls with double cords, 7.25 

Collision Balls ; a set of five lignum-vitae balls, V/ 2 inch diameter, suspended 
upon a metallic bar which is fitted to attach to the pillar of the set of Me- 
chanical Powers, (see cut No. 12,) » 3.50 



SCHOOL APPARATUS 






No. 9. 



No. Price. 

9. Centre of Gravity ; a set of illustrations of centre of gravity, viz. : 

1st. Triangular block, with holes drilled at the angles, from which lines are 
drawn, representing the verticals through the several points of sup- 
port and the common centre of gravity. 
A square block, with similar centres and lines. 
An oblique parallelogram, with centres and lines. 
Two balls of unequal size, with centre in the connecting rod. 

A handle, with steel pin for the above. 
Plumb line. 

Loaded wheel and stand ; a disk of wood which has a mass of lead in- 
laid near one edge, with centres of magnitude and gravity. 
7th. Leaning tower, with movable capital and inclined base ; with the capital 
removed, the vertical of the centre of gravity falls within the base ; 
replace the capital, and the vertical falls beyond the base, conse- 
quently the tower falls ; the centres are drilled to balance upon the 
stand of (5th illustration. 
8th. Double cone and inclined plane ; the cone rolls up the inclined plane, 
the bars of which diverge so that the axis of the cone actually 
descends. 
9th. Horse and rider, with lead ball and stand ; adjusted to balance on the 

legs of the horse 11.00 

10. Centre of Gravity. A set of illustrations selected from No. 9. 

1st. Triangular block. 6th. Loaded wheel. 

3d. Oblique parallelogram. 7th. Leaning tower. 

4th. Balls and rod. 8th. A handle for 1th aud Gth. . . 5.00 



2d. 
3d. 
4th. 

5th. 
Gth. 



LAWS OF MATTER, &C. 




No. 14. 



No. Price. 

11. Illustration of Pulleys, "Wheel and Axle; base and mahogany 

pillar, with screw and nut to confine a metal bar with hooks for the 
following systems of brass pulleys, (each system is balanced) : — 

1st. Fixed pulley and cord, power and weight equal. 

2d. Fixed and movable pulleys, power and weight as 1 to 2. 

3d. Double movable pulleys, power and weight as 1 to 4. With the pul- 
leys, the " system of four single pulleys " can be made (see above cut); 
power and weight as 1 to 2, 4, or 8. 

4th. Wheel and axle, with four diameters, and cords, suspended in a 
frame to attach to the pillar. 

5th. Ship's capstan and levers; a hook is placed in the base to secure a 
fixed pulley ; pass the cord over a pulley on the bar. 

6th. Cords fitted for making the " system of four single pulleys," by 
using those of the above sets. 

7th. A set of weights from 1 to 32 ounces 27.50 

12. Simple and Compound Levers; iron base, handsomely painted; 

mahogany levers and pillars COO 

13. Wedge, Inclined Plane, and Screw; polished inclined plane, car 

with four wheels, cord and pulley for the weight ; screw and iron 
frame ; and wedge 7.50 

14. Set of Mechanical Powers, including Nos. 11, 12, 13 41.00 

Note. — This arrangement for the illustration of the simple machines 
will be found very convenient and complete. The teacher can thus 
have before his class those only that illustrate the lesson, which he 
can show in a conspicuous manner. 



SCHOOL APPARATUS 




^k 



No. 16. 



No. 17. 



No 
15. 



16. 



17, 



18. 



Price. 

Illustration of Pulleys; four systems of pulleys with counterpoises, 
wheel and axle, and capstan, mounted on a polished frame, and set of 
, weights from 1 to 32 ounces 30.00 

Lever Balance and Steelyard; a mahogany beam with knife-edge 

bearings, hooks, base and brass pillar 12.50 

Central Forces ; a metal stand and spindle, an elastic ring with spool for 
a cord ; the ring, in rapid motion, assumes the form of the dotted line 
by the centrifugal force, the spring of the metal representing the 
centripetal force 4-50 

Illustration of the Pendulum ; a bar to attach to the pillar of No. 11. 
Two pendulums of equal length, v/ith balls of lead and boxwood, 
which oscillate in the same time ; two other pendulums, of one fourth 
and one ninth of the proportional length, which oscillate in one half 
and one third the time, proving that the time is as the square root 
of the length • 3.50 



HYDROSTATICS. 



HYDROSTATICS 







No. 26. 



No. 27. 



No. 
20. 



21. 



22. 



23. 



24. 
25. 



20. 



27. 



Price. 

Equilibrium Tubes, or hydrostatic paradox ; four glass vessels of dif- 
ferent forms, connected by a tube within the base, showing- that a liquid 

preserves a level , 4.25 

Note. — Pour into one of the tubes enough of alcohol to fill it, displa- 
cing the water ; the column of alcohol will stand as much higher as its 
specific gravity is less. 

Bottle and Tubes. A closed jar with three tubes, opening upward, 
downward, and laterally, to show that the pressure is equal in each di- 
rection at same depth 3.50 

Glass Cylinder and Plate, to illustrate the upward pressure of liquids; 
the tube is ground to fit the heavy brass plate; hold the plate up by the 
string, and plunge the cylinder in water; the pressure below will then 
sustain it 3.00 

Liquid Adhesion Plate. A glass disk with cord ; considerable force 
is required to lift it from the surface of water; the water below the 
plate will be raised considerably above the level in the vessel 1.50 

Siphon of brass tube 75 

Tantalus Cup, illustrating intermitting springs; fill the cup slowly; 
when the water rises to the bend of the siphon, it will flow and empty 
the cup 2.50 

Glass Balloon and Car, in jar; the balloon is partly filled with water; 
by pressing down the elastic cover, the air above the water is com- 
pressed, and transmits a pressure to the water, by which the air in the 
balloon is also compressed, and more water is forced in through an ori- 
fice, increasing its weight so that it sinks ; remove the hand, the air 
within the balloon expands, water is expelled, and the balloon rises. 
This simple apparatus strikingly illustrates the compressibility and 
elasticity of the air, and the principles of specific gravity 5.00 

Model of Lifting Pump. A strong glass cylinder with brass caps, 

showing the action of the piston and valves 9.00 



10 



SCHOOL APPARATUS. 





No. 28. 



No. 29. 



28. 



29. 



30. 

31. 
32. 
33. 
34. 



35. 



36. 
37. 



Model of Lifting and Force Pumps. Lifting and force pumps on a 
mahogany stand, with large cistern. 
The cylinder of the lifting pump is of glass, showing clearly the piston 
and valves ; a funnel and tube conveys the water again to the cistern. 
The force pump is also of glass, with glass air-chamber; the piston 
and both valves are visible in action; the conden sing-chamber has a 

stopcock and hose, with jet 22.50 

Archimedes' Principle. A brass cylindrical cup, with a bail and hook 
beneath ; a cylinder of brass exactly filling the cup ; and counter- 
poise; suspend the cup with the cylinder enclosed and counterpoise to 
balance of No. 16; then suspend the cylinder by a thread to the hook, 
and let it be immersed in a tumbler of water, and fill the cup with wa- 
ter; it will again be balanced by the counterpoise, proving the buoy- 
ancy of a liquid to equal the weight of the same volume 3.50 

Model of "Water Wheels, overshot, undershot, and breast wheels, 

with water-course neatly made of tin, and painted 12.00 

Hydrometers. Baume's scale for spirit, acids, milk, syrup, &c, .... 1.25 

Hydrometer, universal, with in the middle of the scale 2.50 

Hydrometer, Nicholson's, for specific gravity of solids 6.00 

Ritchie's Illustration of the Hydrostatic Press. A frame of brass ; 
within the base is placed a cylindrical, bellows formed bag of rubber, 
connected by a tube to a rubber globe, fitted with a cap; a cylinder of 
iron, 2>£ inches diameter and 4 inches high, rests upon the bag. FilJ. 
the globe with water, close the cap, and elevate the globe of water; 
the hydrostatic pressure of the column of water will force it into the 
bag, raising the iron cylinder; depress the globe, the weight will force 

the water back into the globe 12.50 

Specific Gravity Balance. A brass beam and scale-pans, brass stand- 
ard and base 17.50 

Model of Barker's Mill. Metal tube, and funnel to attach to No. 65. . 1.25 
Hero's Fountain. 24 inches high, with jet 8.00 



PNEUMATICS. 



PNEUMATICS 




No. 40. 



No. Price. 

40. Ritchie's School Air Pump. The plate is eight inches diameter, and 
forms the top of a cylinder four inches high, which prevents any flex- 
ure or change in its form. The pump cylinder is placed horizontally 
beneath the plate, passing through its cylinder which protects it from 
injury. The inlet tube from the plate into the pump is of large diam- 
eter, and opens into the cylinder below the piston when fully drawn 
out, allowing a free communication from the receiver to the pump, 
without valve or obstruction. The piston is of a new construction, 
and is packed so as to move freely, yet is perfectly tight, and will wear 
a long time uninjured ; the exit valve is simply a disc of oiled silk, 
held in place by a pin in the middle, and covered by a brass dome; the 
valve can be changed if required, in a minute's time. The exit valve 
tube passes to cistern below. The base is furnished with a table 
clamp screw. 

This pump is essentially automatic in its action, and is capable of a 
higher exhaustion than is attainable by the ordinary T-handle pumps. 

In action it is important that the piston be brought into contact with 
each end of the cylinder. The plate must be oiled or greased where 
the receiver touches it; a small quantity of oil flowed around the line 
of contact of the receivers and plate will usually prevent any leak. 
The piston rod should be oiled, and occasionally some oil should be 
poured in the hole in the pump plate; any excess of oil will be carried 
over into the cistern and can be used again. 

The pump is worked with ease, and is warranted to be trustworthy and 
durable 30.00 



12 



SCHOOL APPARATUS, 




No. 41. 



No. Price. 

41. Air Pump, of Ritchie's improved construction, on Leslie's principle, with 

lever, and closed cylinder, by which the pressure of the atmosphere 
is in a great degree removed from the piston. The cylinder is highly 
polished; the piston rod passes through a stuffing box of cup form, 
which is to be half filled with oil; the outer valve is of original con- 
struction, similar to the one adopted in No. 40. The dome, covering 
the valve as well as the cylinder head, can be readily unscrewed by 
the hands. The exit tube passes from a channel round the valve 
through the base into a cistern, to receive any oil that may pass over. 
The'cylinder is 7£ by 2 inches, the plate is 8 inches in diameter 45.00 

42. Plain Receivers. (See cut No. 40.) Quart, 1. 00; two quarts, 1.25; gal- 

lon, 2.00; two gallons 2.75 

43. Capped Receivers. (See cut No. 41.) With brass cap for sliding rod, 

&c. Six quarts, 4 75 ; two gallons 5.50 

44. Cylindrical Jar; to place under receiver 1.50 

45. Sliding Rod; with ball handle and packing screws 2.75 

46. Screw Plug; for closing brass caps, &c 75 

47. Hand Glass, or Bladder Glass, ground at each end; place it upon the 

pump, and cover the opening with the palm of the hand; it will be 
forced down with a pressure of about forty pounds if the glass is 
entirely exhausted. Stretch a piece of thin wet bladder over the large 
end, tie it tightly, and let it dry; put the small end on the plate, the 
bladder will burst with a loud report ; or tie over a piece of vulcanized 
rubber, it will be forced in by atmospheric pressure until it nearly fills 
the interior of the glass 1.25 

48. Ritchie's Improved Condenser; the cylinder is 7 by \\i inches; 

the base cap can be unscrewed by the hand ; a large screw in the thick- 
ness of the cap holds the inlet valve by its flange, while the exit valve 
is secured at its lower end by a pin. The valves are thus protected 
from injury, yet both are readily accessible; both are of oiled silk, and 
hold perfectly tight 9.50 



PNEUMATICS 



13 




No. 50. 





No. 48. 



No. 49. 



No. 53. 



No. 54. 



No. Price 

49. Condensing Chamber, of heavy copper, with stopcock, movable inte- 

rior tube, and water-jet 9.50 

50. Mercury Tunnel, or Mercury Shower; a cup of mahogany with a cyl- 

inder of porous wood ; place upon the hand glass with a tumbler be- 
low j pour some mercury in the cup ; exhaust, and the atmospheric 
pressure will force the mercury through the pores of the wood. . . . 1.50 

51. Expansion Bolt Head, and vial; half fill the vial with water colored 

with litmus or red ink; place under the receiver; the air in the globe 
will expand, and rush out through the water ; then vent the pump and 
the water will nearly fill the bulb 75 

52. Freezing Apparatus ; receiver, pan for acid, improved silvered water 

cup, and supporting frame. Pour a little sulphuric acid into the pan, 
and a little water into the cup ; the water will be frozen by the rapid 
evaporation 4.00 

53. Bacchus Illustration; two glass jars, a brass tube passes from the 

bottom of one, fitting air-tight to its brass cap, and passes over to the 
bottom of the other jar. Nearly fill the closed jar with colored water, 
place under the receiver; the confined air in the first jar will expand 
and drive the water over into the other jar; then vent the pump and 
the water will be driven back again 3.75 

54. Magdeburg Hemispheres, i]/> inches diameter; stopcock, handles, and 

stand; screw the stopcock into the pump plate, exhaust, close the 
stopcock, and screw on the opposite handle; great force will now be 
required to separate the hemispheres 7-50 

55. Rubber Bag and Cap. Put the bag, with very little air in it, under 

the receiver; the confined air will expand and distend the bag 2.25 

56. "Weight and Buoyancy of Air (See cut, No. 40). Brass balance, with 

brass support and stand; globe of three inches diameter, with stop- 
cock, hook, and counterpoise 12.00 

56a. Weights ; in a box, from one decigramme to twenty grammes 3.50 

57- "Water Hammer ; a glass tube containing water in a vacuum, hermet- 
ically sealed; the water strikes with a metallic concussion 1-25 

58. Barometer Tube. A thick tube 33 inches long, closed at one end ; fill 
with mercury, close it tightly with the finger, and plunge it under mer- 
cury in a cup ; remove the finger and the mercury column will fall a 
little, but will remain nearly 30 inches high in the tube 1.50 



14 



SCHOOL APPARATUS, 




No. 59. No. 60. 



No. 61. 



No. 63. 



No. 
59. 



60. 



61. 



62. 
63. 



64. 



65. 



66. 

67. 

68. 
69. 



Price. 

Barometer Apparatus of improved construction. Receiver 33 inches 
high; a glass tube with brass screw collar fitted to a mercury cistern; 
the top of the cistern has a cap and oiled silk valve; exhaust and the 
air will pass out freely through the valve; admit the air and the mer- 
cury will rise to near the barometer height 6.00 

Fountain, a heavy glass receiver 15 inches high, with cap and stopcock; 
a long brass jet and stand; exhaust the bell and plunge the stopcock 
in water, which will be forced up in a jet 8.00 

Upward Pressure Apparatus. A glass cylinder supported upon a tri- 
pod stand, with piston and strap for weight ; the top of the cylinder is 
closed by a plate, which is to be connected to the air-pump by the hose 
No. 62. Exhaust, and the piston will be forced up by the atmospheric 

pressure 11.00 

Note. — The upward and lateral pressure of the air is as strikingly 
illustrated by the Magdeburg hemispheres. 

Rubber Hose, with brass screws to connect No. 61 to air-pump 3.00 

Guinea and Feather Tube. A heavy glass tube with brass caps, stop- 
cock, and stand; a thin disk of metal and several of tissue paper are 
enclosed ; exhaust, and then elevate alternately each end of the tube; 
the tissue paper disks will fall as rapidly as the metal one. The tube 
is fitted with a point for an Aurora Tube. (See No. 131.) 8.00 

Air Gun ; a brass tube with socket to fit a stopcock, to be used with the 
condensing chamber, with balls; drop a ball into the tube, quickly 
turn the stopcock half round, enough air will escape to throw out the 
ball with great force 1.25 

Revolving Jet, with screw to attach to the Condensing Chamber. When 
used as a Barker's Mill, leave off the interior tube, and invert it with- 
in the jar No. 46 3,25 

"Wood Cylinder and Weight, to sink when the air is removed from 

the pores of the wood 25 

Plate Paradox. A brass plate and tube, and mica disk; lay a disk upon 

the plate, and it cannot be blown off. .75 

"Washers for stopcocks, &c . . . . .25 

Oil to use with air pump = .... ... . .25 



HEAT. 



15 



No. 70. 




No. 72. 





K 1P1 


ifi" 


1 1 

m ' 1 


1 



No. 77. 



No. 75. 



No. 76. 



No. 
70. 



71. 



72. 



73. 



74. 



75. 



76. 



77. 



78. 



Price. 
Palm Glass. Two bulbs and connecting' tube, containing" ether in a vac- 
uum, which boils by the heat of the hand. The absorption of heat in 
vaporizing a portion of the ether will be sensibly felt; the bulb in the 

hand will feel cold 1.00 

Pulse Glass. Similar to No. 70, but with one bulb; the other end is cy- 
lindrical; the heat of each pulsation in the hand is marked by a bub- 
ble formed in the tube 1.00 

Ring and Ball, showing the expansion of metals by heat; the ball, 
when cold, passes freely through the ring; heat the ball over a spirit 

lamp, and it will not enter the ring • 2.25 

Bar and Gauge, with handles like No. 72; the bar, when of same tem- 
perature with the gauge exactly fits it ; by Avarming the bar (or by ex- 
posing the gauge to cold), it will not enter. This apparatus is more 

sensitive, and better than No. 72 2.75 

Compound Bar, showing the unequal expansion of different metals; a 
bar of iron and brass riveted together; heat the bar, and it becomes 

curved by the greater expansion of the brass 2.25 

Fire Syringe and Tinder ; showing the heat evolved by the sudden 
compression of air; a brass cylinder and piston, with a cavity for tin- 
der; force the piston down suddenly, and the tinder will be fired. . . 3.00 
Reflectors and Ball. A pair of polished, silver plated concave reflect- 
ors, mounted on metal base, with ball and holder; heat the ball to a 
red heat, and place it in focus of one mirror, and place one bulb of 
No. 70 or 85 ten or twenty feet distant, in the focus of the opposite 
mirror, showing that heat is reflected in the same manner as light. . 12 50 
Wollaston's Steam Engine. A cylinder with a thin copper globe, 
piston and rod, and handle ; pour a little water into the globe, and hold 
it over a spirit lamp ; steam will be generated and drive up the pis- 
ton ; then plunge the globe in cold water; the steam will be condensed 
and the piston forced down by atmospheric pressure. This is a sim- 
ple but beautiful illustration of the low-pressure engine 5.50 

"Wire Gauze, of brass, for experiments with flame, illustrating the Davy 

miner's lamp • *. 75 



16 



SCHOOL APPARATUS 




No. 86. 



No. 90. 



No. 
79. 



80. 



81. 



82. 



83. 
84. 
85. 
86. 



87. 



88. 



89. 
90. 



Price 
Specific Heat. Two balls of copper aud tin of equal weight; pour into 
two thin tumblers the same weight of water, and note the tempera- 
ture by a thermometer; plunge the balls into boiling water, and then 
one in each of the tumblers. It will be found that the copper ball has 
raised the temperature highest, but that in neither is the water raised 
as many degrees as the balls have lost, showing that copper has more 

capacity for heat than tin, but less than water 1.75 

Plates for Radiation and Absorption. Two plates, one bright the 
other black, with stand. Heat the copper ball of No. 7.9, place it mid- 
way between the bulbs of No. 85, and let the plates touch the bulbs ; 
the black will prove to be the best absorber. Place the plates in con- 
tact with the ball, and the black will be the best radiator 2.50 

Cell for Iodine. For solution of iodine in bisulphide of carbon; this 
solution has the property of cutting off totally all heat from a lumi- 
nous source, while it permits obscure heat to pass freely 

Principle of Ventilation. A glass bell, with a tube or chimney, and 
movable diaphragm ; place a short piece of a lighted candle within 
the bell, it will soon be extinguished; put the diaphragm into the 
tube, a circulation takes place, and the candle will burn brightly. . . 3.50 

Thermometer in japanned case; six inch, .75; eight inch, 1.00 

Thermometer for liquids 1.25 

Differential Thermometer, Leslie's, on stand, 3.50 

Conductometer. Brass plate on tripod, six rods of iron, brass, tin, cop- 
per lead and glass; place it over a spirit lamp with phosphorus upon 

the ends of the rods 4.50 

Eolipile. A ball and jet ; heat it over a spirit lamp, plunge it under wa- 
ter so that water will be forced in; heat until the steam issues with 
force ; substitute ether and the jet will burn with a beautiful flame. . 3.50 
Pyrometer. Mahogany frame, with dial and adjusting screw; rods of. 

iron and brass, and two small spirit lamps 7.50 

Psychrometer, or Mason's Hygrometer, with fountain in boxwood scale. 4.00 
Hygrodeik (Edson's) ; a very valuable and convenient adaptation of a 
scale to the Psychrometer, by which all calculations from the formula 
are saved, and the results obtained at a glance. Viz. : — 1st. The 
actual and sensible heat of the room. 2d. The relative amount of 
moisture in the air on a scale of 100 degrees, zero being absolute dry- 
ness, and 100° saturation for the given temperature. 3d. The dew- 
point. 4th. The weight of water in grains present in each cubic foot 
of air. 5th. The force of vapor. By following the indications of this 
instrument, not only health and comfort will be promoted, but also 
economy in the saving of fuel 15.00 



ELECTRICITY 



17 



ELECTRICITY. 




RITCHIE'S PATENT HOLTZ MACHINE. 



The construction and arrangement of our Holtz machine has been much changed 
and improved from that of the original one, and all the later discoveries have been 
introduced into it. 

We have devised a machine of great simplicity, neatness, and power. It consists 
of a stout glass plate supported by mahogany posts on a metal frame, handsomely 
japanned; upon this is sustained a thin glass revolving plate, over which is held a 
sector plate with coatings of paper; on the opposite side of the revolving plates are 
collecting combs, which are connected to two brass arms bearing the discharging 
rods, and also to two Leyden jars, which rest upon the metal frame; a pulley with a 
long shaft is held at one end. of the base, to either end of which the crank may be 
placed; an adjustable, intermediate pulley receives belts to the crank pulley, and to 
one connected with the revolving plate ; a rod armed with combs is held in position so 
that the points are opposite to the farther edge of the paper coatings; a piece of vul- 
canite to excite the machine. 

The power of the Holtz machine is immensely superior to the frictional machine, 
both in quantity and intensity of electricity developed. 



No. 
98. 



99. 



100. 



Price. 

Ritchie's Holtz Machine; revolving plate 14 inches in diameter, 
capable of throwing sparks, in favorable condition of the atmos- 
phere, four to five inches in length. . ... 40 00 

Ritchie's Holtz Machine; revolving plate 10 inches in diaiiu.tr, 

capable of throwing sparks five or six inches in length 15 00 

Cat's Skin, for exciting electricity , 50 

2 



18 



SCHOOL APPARATUS. 






L^ . 




No. 101. 



No. 104. 



No. 111. 



No. 107. 



■lUlilMtlW". - = 
OBSESS* ■ J ii^ 

No. 106. 





No. 103. No. 105. 



No. 110. 



No. Price. 

101. Insulated Support. A brass ball two inches diameter, mounted 

upon a glass pillar, with base; an arm five inches long, with a smaller 
ball, is held by it; upon this can be supported the electric bells, 
image, plates, atmospheric jar, etc 13 50 

102. Friction Cylinder ; of glass, 75 cents; of vulcanite, 1.75 

103. Electroscope. Two pith balls suspended by a thread to a ball and rod, 

with stand; the rod is fitted to the conductor of electrical machine; 

the electroscope shows the presence of electricity on any body. . . . L25 

104. Gold Leaf Electroscope. A glass jar with base and cap, with brass 

stem aud ball; to the stem, on the inside, are suspended two strips 
of gold foil; a slight electrical excitement causes the strips to repel 
each other. Charge the leaves by No. 102 glass rod positively ; bring' 
the electroscope near any excited body; if this is positive the leaves 
diverge more ; if negative, less. . , «... 6.00 

105. Elier. A light wheel balanced upon a point; the arms are pointed an J 

curved ; place it upon the conductor, and when the machine is turned, 
the repulsion between the electricity of the points and that communi- 
cated by the points to the air, causes the wheel to revolve; in a dark 
room the points are luminous 1.75 

106. Electrical Tellurian. Three balls upon centres in the connecting 

wires ; it illustrates the same principal as the flier, and shows the 
revolution of a planet and satellite, 2.50; on insulating stand, . . . . 6.50 

107. Dancing Image Plates. Two metallic plates, connected by silk cords ; 

a hook to suspend to conductor, and chain 3.00 

108. Dancing Images. A pair of pith figures illustrating electrical attrac- 

tion and repulsion 1.00 

109. Head of Hair. A doll's head with long hair, illustrating the rcpulsiou 

of substances similarly charged ; each hair repels every other; the 
hair of a person upon the insulating stool is affected in the same 
manner 2.50 



ELECTKIC1TY 



19 




No. 112. 






No. 114. 



No. 116. 



No. 
110. 



111. 



112. 



113. 



114. 



115. 

116. 
117. 

118. 



Price. 

Insulating Stool; 12 inches square, with cross bars and legs of solid 

glass firmly cemented in 5.50 

Note.— A board laid upon four strong glass tumblers will make a ser- 
viceable insulating stool. 

Electrical Bells. Two bells suspended upon a wire frame; one by 
brass wire, the other by silk cord; the latter has a chain to make con- 
nection with the earth; an insulated ball is alternately attracted and 
repelled between the bells 3.50 

Leyden Jar. A glass jar coated outside aud inside with tin foil; a cap 
of wood supports a brass stem and ball, which connects with the in- 
ner coating. To charge the jar, hold it by the foil and bring the ball 
near the conductor; to discharge, connect by the discharger the outer 
coating with the ball ; pint, 1.50; quart, 2.00; two quarts, 2.75 

Atmospheric Jar; has a hook stem to suspend it to the conductor, to 
show that ajar cannot be charged without a connection by which the 
negative electricity can flow from the earth to the outer coating; the 
jar is charged very slowly, but as electricity passes freely between 
the atmosphere and a point, by placing the ring of points upon the 
jar, it is rapidly charged ; quart, 3.00 

Movable Coating Jar, consists of a jar with closely fitting metallic 
coatings ; charge the jar as No. 112; then with a glass rod or the dis- 
charger, lift out the inner coating by its hook; the jar may now be 
safely taken from the outer vessel; no trace of electricity will remain 
in the two coatings, and if the jar is touched on both sides, only the 
surface touched will be discharged; now replace the parts, lifting the 
inner coating as before; the jar may now be discharged, shoAvingthat 
the electricity is accumulated on the surface of the glass, being re- 
tained by the mutual attraction of the negative and positive fluids on 
the opposite sides. The coatings serve only as conductors 3.75 

Electrometer Jar, differs from No. 112 in having a discharging rod and 
ball which may be adjusted near the outer foil ; when the jar is charged 
to a sufficient intensity (greater or less in proportion to the distance 
of the ball), the discharge takes place; quart, 2.50; two quarts, . . . 

Diamond Jar. The coatings on either side are small squares of foil; 
each perforated to show the opposite points; the discharge of the jar 
is very beautiful in a dark room; quart, 

Lightning Plate, is a large plate of glass, coated on one side with foil, 
and on the reverse with brass tilings ; bring the chain from the rub- 
bers of No. 101, or the earth chain of No. 100, to one edge of the fil- 
ings, and a chain from conductor to the opposite edge; the current 
will pass in beautiful zigzag lines. The plate can be charged like a 
Leyden jar; the discharge is very brilliant 2.00 

Amalgam for the rubbers of the electrical machine, in box, .25 and . . .50 



3.25 



3.00 



20 



SCHOOL APPARATUS. 




No. 119. 



No. 120. 



No. 124. No. 123. No. 122. 



No. Price 

119. Improved set of Leyden Jars ; consists of a two quart electrometer 

jar, No. 115 ; a quart atmospheric jar, No. 113, and a metallic plate ; 
remove the discharging- rod and the ball from No. 115, and screw in 
its place the plate ; remove the ring from No. 113, and set it on the 
plate, and thus form a double jar .; connect the stem of upper jar with 
the [machine, and the foil of lower with the earth ; the inside of the 
upper and outside of the lower will receive positive electricity ; each 
may be discharged separately, or both together. Again connect the 
stem of lower with the machine ; this alone is charged, (unless the 
ball of upper jar is put in connection with the earth ;) then connect 
lower outer coating with ball of upper, and the lower one will be par- 
tially discharged in charging the upper one, &c $6.50 

120. Stand and Bells; A basement with pillar and bell, and a similar bell 

to screw to the stem of a Leyden jar ; a little ball suspended between 
the bells will be alternately attracted and repelled between them, vi- 
brating for a long time; fitted to Nos. 112 or 119 5.00 

121. Ether Spoon ; a metallic cup with a brass knob in the centre ; cover 

the knob with ether or warm alcohol '. a spark from conductor to 
the knob will fire the ether ; a person standing upon the insulating 
stool, may fire it by his finger or by an icicle held in the hand 1.25 

122. Spiral Spotted Tube and stand, 20 inches high ; the electric current 

passes through the tube from spot to spot in beautiful scintillations ; 
the tube may be held in the hand, or let the chain from the rubbers 
pass to the lower cap 4.00 

123. Egg Stand; for illuminating eggs ; a b«se with movable bars and s* hid- 

ing rod, for supporting eggs; the discharge of a Leyden jar beauti- 
fully illuminates the eggs, the yolk and white will be completely 
mingled 2.50 

124. Discharger ; a curved brass wire and balls upon a large glass handle. 

and a piece of chain with a hook to attach to one arm, to use when a 

longer reach is desired 3.50 

124A. Jointed Discharger; large handle, with long curved rods, and hinged 

joint 5.25 

125. Gas Pistol, fgr firing a mixture of hydrogen gas and air by the electric 

spark 1.00 



ELECTRICITY. 



21 




No. 128. 



No. 129. 



No. 130. 



No. Price. 

126. Powder Bomb; illustrating the effect of passing- the electric current 

through water ; pour a thimble full of powder into the bomb, place a 
charged jar upon the chain of the bomb, thoroughly wet the cord and 
attach it to one arm of the discharger, bring the other arm to the 
ball of the jar, and the powder will be fired ; if the wet string is not 
in the circuit the powder will not be fired $2.0C 

127. Sportsman and Birds ; put the birds on the electrometer jar ; at the 

instant of discharge, the birds will fall 1.50 

128. Obelisk; illustrating the lightning rod; a pyramid of several parts, 

resting upon a pedestal ; a lightning rod passes down through a mova- 
ble block ; if this is placed so that the rod is not continuous, it is 
thrown out by the discharge of a Leyden jar, and the obelisk falls. 5.00 

129. Dancing Balls ; 1 dozen pith balls in box ; place the receiver, No. 45, 

on a metal surface ; screw the plate of No. 119 on the sliding rod, and 
connect with machine ; or hold a glass vessel so that a piece of chain 
from the conductor will fall inside, which will charge the surface of 
the glass ; then throw in the balls 25 

130. Gassiot's Cascade ; a glass vase, coated on the inside with tin foil ; 

place it under the receiver, and pass the sliding rod through apiece 
of glass tube down to the foil ; let the rubber chain pass to the pump 
plate. The electrical discharge is very beautiful 2.50 

131. Aurora Tube, (see No. 63 ;) exhaust the tube and pass the electrical 

current through it; a beautiful auroral light will fill the tube; then 
place the ball of the tube at different striking distances from the con- 
ductor ; the electricity will flow in slender streams, braiding on the 
inner surface of the glass ; the effect will be changed by gradually 
admitting the air to the tube 8.00 

132. Luminous Points ; two sets of points, to screw into the pump and to 

the sliding rod ; exhaust the bell, and connect the sliding rod to the 
electrical machine ; the discharge between the points, and the flu- 
orescence surrounding the wires, are verv beautiful „ 3.00 



22 



SCHOOL APPARATUS. 



MAGNETICS. 




No. 146. 



No. 147. 



No. 151. 



No. Price 

140. Bar Magnet; a flat steel permanent magnet, with poles marked N and 

S ; the lines which show the resultant action of the magnetic forces 
are shown by laying a plate of glass over the bar, and sprinkling fil- 
ings from a sieve ; these lines are called magnetic curves 1.00 

141. Horse Shoe Magnet, or U magnet, with armature of soft iron; the 

glass plate and filings exhibit the magnetic curves. When not in use 

the armature should be kept upon the poles of the magnet, 1.00 and . 1.50 

142. Magnet and "Wheel Armature; the arms of the magnet are ten 

inches in length; a cylindrical armature, with a brass wheel 3.75 

143. Magnetic Needle, with brass stand and point; the needle has a bell- 

metal centre, and is balanced to be acted upon by the earth's magnet- 
ism, as also by the attraction and repulsion of another magnet, show- 
ing that poles of opposite names attract, while those of same name 
repel each other 1 .50 

144. Dipping Needle, on stand 8.50 

145. Voltaic Pair. A plate of copper and one of zinc, connected by a cop- 

per wire and glass jar. In use, the zinc must be amalgamated with 
mercury; use ten volumes of water to one of sulphuric acid 1.50 

146. Smee's Battery. A glass jar with two thick plates of zinc, between 

which is a sheet of platinized metal. Pole cups are connected to each. 
Fill the jar with water, with one tenth its volume of sulphuric acid; 
the zinc must be kept well amalgamated with mercury 4, 50 

147. Bunsen's Battery, is composed of an outer jar nine by seven inches 

diameter, a zinc cylinder nine inches by five in diameter ; a porous 
cell of unglaced earthen ware, within which is a bar of graphite. 
Strong copper ribbons are attached to the zinc and carbon by screw 
clamps. The porous cell is to be filled with nitric acid, the outer cell 
with a mixture of ten parts by volume of water, to one of sulphuric 
acid. The zinc must be kept well amalgamated 4.50 



MAGNETICS. 



23 




No. 152. 



No. 1G2. 



No. Price. 

148. Thermo Plates, German silver and bismuth, for development of elec- 

tricity by heat; single pair, 75 

149. Thermo Pile. A series of pairs of plates connect the wires to the pole 

cups of No. 158. Heat one end of the pile moderately, keeping- the 
opposite end cool; the electricity excited at the soldered junctions of 
the two metals will cause a deflection of the needle of the galvanom- 
eter; 3.00 and 5.00 

150. Powder Cup. Brass cup, with insulated wires connected by a piece of 

fine platinum wire 1.75 

151. Contracting Helix. Base and pillar, with adjusting screw, a spiral of 

copper wire, and glass mercury cup; connect the pole cups to the 
battery ; the current through the helix will cause the spires to attract 
each other, lifting the point out of the mercury with a spark; the 
current is thus broken, the attraction ceases, and the point again dips 
into the mercury; the wire thus vibrates rapidly; if the battery cur- 
rent passes also through the coil or helix of a large electro magnet, 
No. 153 or No. 155, the brilliancy of the spark will be much in- 
creased 5.50 

152. Decomposing Cell. A glass cup, with tubes and pole cups, from which 

platinum wires extend into the tubes ; pour acidulated water into the 
cup ; fill and invert the tubes ; the action of the battery will decom- 
pose water, and the gases will be collected in the tubes. The one 
connected to the positive pole of the battery (the carbon) being filled 
with oxygen, and the other with hydrogen; 3.25 and 5.25 

153. Electro-Magnet. A bent bar of soft iron, with two helices of insu- 

lated copper wire; the iron becomes a powerful magnet when in the 
circuit of a battery, but ceases to be so the instant that the battery 
connection is broken ; 2.50 and 3.50 

154. Heliacal King. Two semi-circular pieces of soft iron, with ring han- 

dles, and a helix of copper wire ; connect the helix with the battery, 

and great force will be required to separate the ring 4.25 

155. Lifting Coil. A large and thick helix and an iron rod; connect the 

wire to the battery, and bring the end of the iron rod below the coil, 

and it will be drawn in and held in suspension. 3.00 and 4.00 

156. Revolving Magnet is a steel, permanent magnet, between the poles 

of which is a straight electro-magnet on a spindle; the current is re- 
ceived through pole cups, and passes to the electro-magnet through 
a pole changer on the spindle, arranged so that at each revolution 
each end of the electro-magnet becomes alternately a north and south 
pole, and is therefore alternately attracted and repelled by the per- 
manent magnet, producing a revolution of astonishing rapidity. . , . 8.00 



24 



SCHOOL APPARATUS. 




No. 163. 





No. 157. 




|MJiiiiiiiiiiiiiii!iiiniiiiii[ii 

No. 156. No. 160. 

157. Galvanometer (Oersted's). A base and pillar supporting a wire frame, 

within which is placed a magnetic needle. The wire has three pole 
cups arranged so that the battery current may pass above, below, or 
around the needle, showing the influence of the current upon the nee- 
dle, and measuring the force of the voltaic current by the amount of 
deflection of the needle; the frame must be placed north and south. . .4.75 

158. G-alvanometer, compass form; a flat helix surrounds the needle, by 

which the current passes many times around it, increasing the power 

of deflection 6.50 

159. Telegraph Model. Upon a base is placed an electro-magnet, with its 

armature attached to a spring; a point upon the spring marks the pa- 
per as it is drawn out from the reel; a signal key upon a separate 
base, with pole cups, and a long wire to extend around the room. 
Connect one pole of the battery to the model, a wire from the model 
to the signal key, and a wire from it to the other pole of the battery. 
When the signal key is pressed down, the armature instantly is drawn 
down, marking the paper 9.00 

160. Telegraph Model, with the signal key on the same base 8.00 

161. Model of Relay Magnet. A base and an electro-magnet of fine wire, 

over which is a movable lever, adjustable by a spring for making 
and breaking a battery circuit. Use No. 146 for the relay electro-mag- 
net, and No. 145 for telegraph model. These models will show plain- 
ly the whole operation of the Electric Telegraph 9.50 

162. Separable Helices for induction. The primary helix is supported up- 

on a base, with a vibrating and a rasp electrotome ; the core is of iron 
wires. The secondary helix is a separate bobbin, with pole cups. 
The power of the induced current is in proportion to the number of 
iron wires used 18.00 

163. Double Helices, or shocker; similar in construction to No. 162, with 

vibrating electrotome. The core is a bundle of iron wires, which can 

be drawn out, regulating the intensity of the shock 8.50 

164. Handles, with insulated wires for shocker „.,...„ 2.00 



ELECTKICIT Y. 25 




No. 165. 



RITCHIE'S IMPROVED INDUCTION COIL. 

One of the most important instruments which have been brought out for many 
years, is the Induction Coil, by which all the effects of static electricity are produced 
from the battery. Its power is immensely greater than the electrical machine; the 
discharges may be made so rapidly as to appear a continuous flow, and with quantity 
so great that a Lcyden jar can be charged and discharged as rapidly as the ear can 
distinguish sounds. It is not affected by the state of the atmosphere, and occupies a 
small space; the battery used is Bunsen's, of intensity of only two to four cells. 

Previous to the invention by Ritchie of his mode of winding and insulating the 
helices, the longest sparks obtained in Paris were less than an inch. By his improve- 
ment, not only was the instrument rendered capable of throwing sparks of fifteen 
inches or more, but the quantity, or volume, is greatly increased. The mode by which 
this was effected was published in Silliman's Journal, and copied into the Philosoph- 
ical Magazine, of London, and other scientific journals of Europe. 



No. Price. 

165. Induction Coil, mounted upon a mahogany base; the helix is covered 

with silk velvet, and rests upon a mahogany pedestal, and is finely 
finished. Capable of throwing the spark 6 inches 337.50 

166. Induction Coil, mounted similar to No. 165, capable of giving sparks 

of 4 inches in length 225.00 

167. Induction Coil, enclosed in a mahogany case of cubical form, mounted 

upon a base; the break-piece and pole cups for battery current, are 
placed on the base, the dischargers upon the top, the helices, and 
other portions of the instrument cannot be shown. Capable of throw- 
ing the spark four inches 200.00 

168. Induction Coil, similar to No. 167, three inch spark 150.00 

169. Induction Coil, similar to No. 167, two inch spark 100.00 



26 



SCHOOL APPARATUS. 



ACOUSTICS. 




RITCHIE'S IMPROVED SONOMETER. 

The case is of mahogany, 40 inches in length, with sounding-board of spruce, fitted 
for two wires, with tension-keys and wrench, and a brass lever with two weights (1 to 
4), for measuring the tension (the upper line of figures is for the smaller, and the 
lower line for the greater weight). Two scales divided to the diatonic scale, with 
letters and syllables for the intervals of tones and semitones, and the ratio of length 
of cord, and number of vibrations ; and a scale of sixty equal parts, with the numbers 
for division into two, three, four, eight, &c, with movable bridges for one or both 
wires to rest upon. 

To produce the notes of the scale, move the bridge to the letters on 'the scale, 
and sound with the bow. 

For the experiment to show the law that the rapidity of vibration is as the square 
root of the tension, attach one wire to the lever, place the weight on some number 
and tighten the wire until the lever is brought to a level, and tune the other wire to 
unison ; then change the weight to a number on the lever corresponding to a chord ; 
thus, from 2 to 8 will be an octave ; 1 to 16, two octaves ; 4 to 9, a fifth. 

For the experiment to show that the rapidity of vibration is inversely as the square 
root of its density, place the large wire, which is four times as heavy, on the lever, 
and the weight to 16; tune the other wire to unison, then change the large wire for 
one of same size as the second one, and raise the weight as before- it will sound an 
octave higher; change weight to 4 and it will give the unison. 

In changing considerably the weight, it will be necessary to tighten or loosen the 
screw to allow for the stretching of the wire. 

For producing overtones, or harmonics, touch with a feather, or lightly with the 
finger, the wire at one of the equal divisions, and draw the bow gently across it; the 
wire will vibrate between the feather and fixed bridge, and also in equal divisions on 
the other side of the feather, but having points of rest, or nodes, at the divisions : 
e. g., touch the feather at 20, another node will be at 40; or touch at 12, other nodes 
will appear at 24, 36, and 48, dividing the wire into three or five equal portions, vibrat- 
ing at equal times, and sounding the tone of the second and fourth harmonic of the 
fundamental note. A box of paper riders, blue and red, arc sent to place on the wire 
before sounding; put some on the nodes, which will remain still, and some of another 
color on intermediate places, which will be instantly thrown off. 

For showing sympathetic vibrations, tune one wire to unison or octave to the organ 
pipe ; or sound the note with the voice, and the wire will be thrown into vibration 
and distinctly heard;. it is essential that the unison or chord be perfect, or the wire 
will not respond. Draw the piston of the pipe while sounding it; the wire will 
catch and respond to the note which was for the instant of same number of vibrations. 
By tuning the wires to near an unison, the effects of interference, or beats, are pro- 
duced. 



No. Price. 

180. Sonometer, with a set of wires, wrench, lever and weights 35.00 

181. Sonometer, with wires and wrench the same as above, without the 

lover and weights. . 25.00 



ACOUSTICS 



27 






No. 182. No. 1S3. No. 187. 



No - Price 

182. Bevolving Toothed "Wheel. A heavy brass wheel supported in an 

iron frame and pedestal; revolve it by a cord wound around the axis, 
and hold a card against the teeth; a shrill musical tone will be pro- 
duced, gradually falling- in pitch as the speed is lessened 7.5o 

183. Iron Screw Press, for confining plates and rods for vibration, with 

table clamp screw 7 50 

184. Brass Plate for vibration; hold it by the middle or other point, in the 

Screw Press; draw the bow across the edge, and from a sand box 
held high above, scatter equally over the plate a small quantity of fine 
black writing sand, which will at once collect into fine lines, showing' 
the nodes, and forming beautiful figures and curves ; these are most 
readily obtained by touching the plate at one or two points with the 
finger while exciting it by the bow 3.50 

185. Brass Bod for longitudinal vibrations, with clamp to hold it in No. 

183, stand, and an ivory ball. Vibrate by rubbing the rod lengthwise 
with a piece of resined leather; place the stand so that the ball 
touches the end of the rod ; it will be violently repelled 3.75 

186. Longitudinal Vibration of Bods ; four wooden rods fixed at one end 

in a bar, to be held by No. 183. They are tuned to 1st, 3d, 5th, and 8th. 3.50 

187. Diapason, or tuning fork on sounding case. The fork and case are both 

tuned to the same note, C 3 =512 vibrations per second ; excite the fork 
with the bow. It can be removed from the case for experiments with 
the organ pipe or tubes ; the reinforcement of sound by bringing it 
over the open end of the case, or Resonant Jar, is very marked. . . . 11.00 

188. Violoncello Bow, for vibrating plates, &c 2.00 

189. Glass Tubes of G, 3, and \y 2 inches in length, for producing a vibration 

by blowing across the open ends. .,,.,, 75 

190. Besonant Jar, 18 inches deep, to be partly filled with water, to be used 

with the tuning fork 2.00 

191. Organ Pipe, with movable sliding piston, giving two octaves, and also 

showing the effect of an open and a closed pipe. The notes of the di- 
atonic scale are marked on the piston 4.50 

192. Organ Beed Pipe. A beating reed enclosed in a glass chamber, 

with a sliding rest, varying the vibrating- length of reed 4.75 

193. Trevelyan's Apparatus. A brass rocker with rod and ball and block 

of lead ; heat the rocker and lay it upon the block ; set it in motion 

and it will vibrate so rapidly as to produce a clear musical tone. . . . 5.00 

194. Bell in Vacuum, with supporting frame and stand. The bell is sus- 

tained upon the frame by silk cords, to prevent the transmission of the 
vibration through the support. In use, screw the frame into the 
pump-plate, and ring by the Sliding-rod 3.50 

195. Kaleidophone : a silvered ball supported upon a slender steel wire upon 

a heavy iron base, showing the stiperposition of vibrations. Pluck the 
ball and give it a wide vibration ; then strike the wire near the base, 
to right or left, a quick, light blow, thus giving it a vibration in anoth- 
er direction. By varying the blows, the reflected sunlight from the 
ball will give most beautiful curves and figures 2.50 

196. Jet for singing flame to attach to Hydrogen Generator „ 1.00 



28 SCHOOL APPARATUS 



OPTICS. 






No. 212. No. 202. No. 213. 

No. Price. 

201. Prism, finely polished; three inch, 1.00; four inch 1.50; five inch, . . . 2.00 

202. Mounted Prism, suspended by points in frame, Vith movable joint and 

stand, so that it may be adjusted to a beam of light 6.00 

203. Achromatic Prism. A pair of flint and crown glass 7.50 

204. Prismatic Lens, or multiplying glass, mounted in tube; the lens is 

ground with a great number of plane faces 75 

205. Neutralizing Lenses. Pair of double convex and concave lenses. . . 3.00 

206. Neutralizing Lenses. Set of four double and plano-convex and con- 

cave lenses 6.00 

207- Condensing Lens, mounted on elevating stand 10.00 

208. Convex and Concave Mirrors. Ground and polished silvered 

lenses, in frame; four inch, 4.50; six inch, 6.50 

209. Cylindrical Mirrors, similar to No. 208; four inch, 3.00; six inch, . . 4.00 

210. Multiplying Mirrors. Four inch, 3.00; six inch, 4.00 

211. Mounted Mirror, on stand, to use with a beam of light through a 

shutter, &c 4.25 

212. Model of the Eye, dissected, showing the coats, retina, iris, crystal- 

line lens, &c, with stand 8.00 

213. Illustration of long, short, and perfect sight, the projection and inver- 

sion of the image on the retina, and march of the rays through the 
crystalline lens , , 7.00 

214. Revolving Disk Apparatus. Mahogany base, metal frame, with 

pulleys and crank; a shaft, with screws for confining disks 9.00 

215. Set of Disks. Circles of cardboard and paper of brilliant colors, includ- 

ing Newton's Disk and forms to show the gradual blending of one 
color into another. One set of paper is cut in such manner that they 
can be arranged so that any combination of the colors can be made in 
the circle 2.50 

216. Newton's Disk. A card to revolve by the twisting of a double cord 

between the hands 75 

217. Newton's Rings Apparatus. A lens and plate of glass mounted in 

brass cell with screws 6.50 

218. Zoetrope. A revolving cylinder with a series of open slits, to produce 

the effect of motion by successive pictures seen through the slits. . . fi.00 

219. Stereoscope, Dr. Holmes' form; the eyes are shaded, but the picture is 

placed on a sliding bar in open light; 2.00 and 3.00 

220. Photographic Pictures. Buildings, landscapes, figures, statues, &c, 

plain and colored ; from .15 to 50 

221. Compound Microscope, with adjustable draw tube, double system of 

objectives, in mahogany box 4.50 

222. Compound Microscope, adjustable tube, with condensing lens, and 

triple system of objectives, in mahogany box 8.00 



C H E M I S T R Y . 



29 



CHEMISTSY. 





i 




' 








ST 




fV: 





No. 242. 



No Price. 

241. Gasometers. A pair, of copper, -with side tubes enclosing- balance 

weights, mounted on base with casters ; brass tubes, -with stop-cocks; 
cylindrical pressure weights; the bells 7 1 ! inches diameter by 17 
inches in height 70.00 

242. Gasometer. Cylindrical bell and cistern, made of thick, galvanized, 

japanned metal, and painted with a preparation nearly insoluble. A 
movable metal crane, with pulleys and balance weight made in sec- 
tions, by removing one or more a corresponding pressure is exerted 
on the gas : the bell is 16 inches in diameter, and 26 inches high. Ca- 
pacity 22 gallons, and is warranted to be strong and durable. . . . * 35.00 

243. Gasometer. Similar to No. 212; the bell is 11 inches diameter, and 24 

inches high 30.00 

244. Pneumatic Trough, of stout, galvanized iron; 20 inches long by 15 

wide, and 12 inches deep, with movable shelf; japanned 9.50 

245. Gas Bag, of square form, of vulcanized rubber-cloth, with socket, IS by 

20 inches; capacity, 15 gallons . . ... 8.25 

246. Gas Bag, with socket, 24 by 30 inches; capacity, 35 gallons 12.00 

247. Gas Bag, with socket, CO by 40 inches; capacity, 55 gallons « . 15.00 

248. Gas Bags of rubber, oval, 1 to 4 gals., with sockets, 2.50 to 5.25 

249. Hydrogen Generator of glass, with inverted bell and stop-cock, a 

copper basket for granulated zinc, and a solid ball of zinc; the cover 

is held by screws beneath a flange 9.00 



30 



SCHOOL APPARATUS. 






No. 315. 



No. 275. 



No. 249. 



No. Price. 

250. Gas Generator of glass, with inverted bell, basket for zinc; the bell is 

attached to a rubber tube, with nipper tap 5.00 

251. Oxygen Flask of copper, thick bottom, screw cap; one quart, .... 5.50 

252. Oxygen Flask, similar to above with gallows screw cap 8.00 

253. Bottle Generator, pint, with rubber cork and tubes 1.00 

254. Nitric Oxide Bell and Jar; the jar is ten inches by four in diameter, 

the bell one half its capacity; both ground to fit a glass plate. . . . 2.50 

255. Oxy Hydrogen Concentric Jet with adjustable lime-holder, and 

gallows screw connections 18 00 

256. Rubber Hose to connect oxy-hydrogen jet to Gasometers or bags, each 

six feet long, with brass sockets . 0.00 

257. Platinum Sponge, jet and holder to attach to No. 240. 1.75 

258. Bottles and Tube for illustrating the diffusion of gases; two bottles 

with rubber corks, connected by a glass tube 1.00 

259. Mercury. The price is variable; our charge will depend on its commer- 

cial value. At present it is, per pound, 1 00 

260. U Tube, with one end closed, tubulated near the bend, to which is at- 

tached a piece of rubber tube with a nipper tap 2.50 

261. Glass Cylinder, with foot, 7 by \y z inches, ground mouth and plate. . 1.50 

262. Glass Cylinder, with foot, 5 by 1 inch diameter, and plate 1.00 

263. Flat Glass Dish, 9 inches diameter, 2 inches deep 1.50 

264. Cylindrical Jar, with ground edge ; two quarts 1.50 

265. Endosmeter, or osmose apparatus; a glass bell over which to tie a 

membrane, with glass tube and rubber cork 1.75 

266. Porous Cup and Tube, for osmose of gases 1.00 

267. Chlorine Tube, of glass, fifteen inches long, closed at one end; an in- 

terior jet tube with rubber to connect to a funnel 1.50 

268. Eudometer, a U tube closed at one end, with platinum electrodes for 

exploding gases; plain, 3.00; graduated, 4.00 

269. Rubber Corks, assorted to one inch diameter , one dozen in box 35 

270. Bunsen's Burner, with stand 1.50 

271. Evaporating Dishes, porcelain, 33, 40, 50, and 00 

272. Chalk Cup, 2 inches by \ x / z diameter 50 

273. Nipper Tap, or spring stopcock for closing tubes; 35 cents and 50 

274. "Wash Bottle, with tubes and rubber stopper 1.75 

275. Lamp Stand, with three bows and binding screws, 2.00, four bows, . 2.25 

276. Iron Chimney for lamp 35 

277. Rubber Tubing, of calibre from eighth to half inch; per foot, 12 to . .35 

278. Cork Borers; set of three, 2 25; set of six, 3.25 

279. Hydrogen Balloons, of goldbeater's skin , 

280. Pendent Spoon and Rod, copper, 50 cents ; platinum, 1.50 

281. Retort Holder, base and pillar, with two pair of spring and screw jaws 

for holding tubes, retorts, &c 3.50 



CHEMISTRY. 31 

No. Price. 

282. Evaporating Dishes, porcelain, nosts of six 2.00 

283. Hessian Crucibles, in nest, , 25 

284. Porcelain Mortar and Pestle; 1.00 to 3.00 

285. Agate Mortar and Pestle; 1.50 to 7.00 

286. Sheet Rubber, piece, for square foot, 50 

287. Dissolved Rubber, in tin boxes, 75 

2S8. Crucible Tongs, of iron; 1.00 and 2.50 

289. Sefstroem's Retort Solder, wood clamps, mounted on iron stand. . . 5. 00 

290. Nipper Tube Holder, wood screw clamps with cork jaws 3.00 

291. Copper Alcohol Lamp, with five wicks 2.25 

202. Spirit Lamp, with ground cap 1.00 

293. Plain Mouth Blowpipe, of brass 50 

294. Blowpipe, with condensing bulb 1.50 

295. Test Tubes, with mahogany stands; 12 tubes, 2.00 and 3.25 

296. Mouthpiece for inhaling gas 2.00 

297. Filtering Paper, in packages; 75 cents to 1.00 



Chemical Glass Ware. 

298. Receivers of different forms, see Pneumatics. 

299. Hydrometer Jar, with foot and lip 1.25 

300. Bolt Heads, or Matrass, pint, fifty cents; quart 75 

301. Funnels, gill, 25 cents; half pint, 35 cents ; pint, 45 cents; quart, CO 

302. Graduated Ounce Measure; 2 oz. C5 cents; 4 oz. 75 cents; S oz. . . . 1.00 

303. Stirring Rods, set of six 50 

304. Safety Tubes; straight, 25: bent with bulbs, 60 

305. Pipette, or Dropping Tube ; 25 and 50 

306. Two Bulbs and Tube, Brand's, for condensation, 75 

307. Glass Chemical Tubes; per pound, 75 cents to 1.25 

30S. Glass Barometer Tubes, small and large, per pound, 1.50 

309. Rupert's Drops, unannealed glass, per dozen, 1.00 

310. Bologna Vials, unannealed; per dozen, 2.25 



Bohemian Hard Glass without Lead. 

311. Retorts; half pint, 40 cents ; pint, 55 cents ; quart, 65 

312. Retorts; tubulated, 3 oz., 40 cents; 4oz., 50 cents; half pint, 60 cents; 

pint, 76 cents; quart, 1.00 

313. Flasks, with rim necks for corks, uniformly thin throughout; 4 ounce, 

30 cents; half pint, 35 cents; pint, 50 cents; quart, 65 

314. Digesting Flasks, with flat bottoms and rim neck; 2 oz., 30 cents; 4 oz. 

30 cents : half pint, 35 cents ; pint, 50 cents ; quart, 65 

315. Woulfe's Bottles, with three necks; piuts, 1.25; quarts, ....... 1.50 

316. Globe Receivers, tubulated; half pint, 50 cent; pint, 65 cents; quart,. .75 

317. Beaker Glasses, in nest; 1.25 to 3.50 

31S. Test Tubes, with rim and lip; per dozen, 50 cents to 1.25 



329. Geometrical Solids. Set of thirteen, including three and six-sided 

prisms, cylinders, cone, pyramid, frustums of cone and pyramid, 
sphere, hemisphere, oblate and prolate spheroids, neatly made in fine 
wood, and in box 2.00 

330. Models of Crystals. Thirteen pieces, giving the fundamental forms, 

according to Dana, in large size 3.25 

331. Cube Root Solids, illustrating the extraction of square and cube roots, 

of mahogany, in box 1.25 

332- Set of 64 inch Cubes, for same illustrations in box 1=75 



SELECTIONS 



OF 



SCHOOL APPARATUS, 

COMPILED FKOM THE 

CATALOGUE. 



SET No. 1. 



Laws of Matter. 

Price. 

Inertia 1.75 

Capillary Tubes 75 

Collision Balls 3.50 

Centre of Gravity 5.00 

Illustration of Pulleys 27.50 

Central Forces 4.50 

Hydrostatics. 

Equilibrium Tubes 4.25 

Cylinder and Plate 3.00 

Siphon 75 

Tantalus's Cup 2.50 

Lifting- Pump 9.00 

Archimedes Principle 3.50 

Pneumatics. 

Air Pump 30.00 

Receiver 1.00 

Receiver 2.00 

Screw Plug 75 

Hand Glass 1.25 

Bolt Head 75 

Bacchus Illustration 3.75 

7.50 

1.50 

8.00 

.25 

.25 

.25 



Magdeburg Hemispheres. 

Barometer Tube 

Guinea and Feather Tube. 
Cylinder and Weight. . . 

Washers , 

Oil 



73. 

74. 

75. 
70. 
78. 
86. 
292. 



Heat. 

Bar and Gauge 2.75 

Compound Bar 2.25 

Fire Syringe. 3.00 

Reflectors 12.50 

Wire Gauze 75 

Conductometcr 4.50 

Spirit Lamp 1.00 



Electricity. 

No. Price. 

98. Holtz Machine 40.00 

100. Cat's Skin. 50 

101. Insulated Support 13.50 

103. Electroscope. 1.25 

105. Flier 1.75 

111. Set of Bells 3.50 

112. Leyden Jar 2.00 

121. Ether Spoon 1.25 

122. Spiral Tube 4.00 

124. Discharger 3.50 

Magnetics. 

140. Bar Magnet 1.00 

143. Needle and Stand 1.50 

147. Battery 4.50 

150. Powder Cup 1.75 

153. Electro Magnet 2.50 

154. Heliacal Ring 4.25 

156. Revolving Magnet 8.00 

163. Shocker 8.50 

164. Handles and Wires 2.00 



Optics. 
201. Prism 

204. Prismatic Lens. . . . 

205. Set of Lenses. . . . 
212. Model of Eye. . . . 
218. Zoetrope 



2.00 
.75 
3.00 
8.00 
6.00 



Recapitulation. 

Laws of Matter 43.00 

Hydrostatics 23.00 

Pneumatics 57.25 

Heat. 26.75 

Electricity 71.25 

Magnetics 34.00 

Optics 19.75 



$275.00 






SCHOOL APPARATUS 



33 



SET No. 2. 

Arranged for and adopted by the City School Committee, for the 

BOSTON GRAMMAR SCHOOLS. 



No. 

2. 

3. 

4. 

6. 

8. 
10. 
11. 
12. 
17. 
18. 



70. 
73. 
74. 

76. 
78. 
82. 
86. 
292. 



100. 
101. 
102. 
103. 
105. 
110. 
114. 



Laws of Matter. 

Price. 

Lead Hemisphere 1.25 

Inertia Apparatus 1.75 

Capillary Tubes 75 

Capillary Plates 1.50 

Collision Balls 3.50 

Centre of Gravity 5.00 

Illustration of Pulleys 27.50 

Illustration of Levers 6.00 

Central Forces 4.50 

Illustration of the Pendulum. 3.50 



Hydrostatics. 

Equilibrium Tubes 4.25 

Upward Pressure of Liquids. . 3.00 

Siphon 75 

Tantalus's Cup '. 2.50 

Model of Pumps 22.50 

Archimedes Principle 3.50 



Pneumatics. 

Air Pump 30 

Receiver . 1 

Receiver 4 

Sliding Rod 2 

Screw Plugs 

Hand Glass 1 

Expansion Bolthead 

Magdeburg Hemispheres. ... 7 

Weight and Buoyancy 12 

Barometer Tube 1 

Guinea and Feather Tube. . . 8 

Washers 

Oil 



00 



Heat. 

Palm Glass 1.00 

Bar and Gauge 2.7d 

Compound Bar 2.25 

Reflectors 12.50 

Wire Gauze 75 

Ventilation 3.50 

Conductometer 4.50 

Spirit Lamp 1.00 



Electricity. 

Holtz Machine 

Cat's Skin 

Insulated Support. . . 
Friction Cylinder. 



. . . 45.00 

... .50 

. . . 13.50 

... .75 

Electroscope 1.25 

Flier 1.75 

Insulating Stool 5.50 

Movable Coating Jar 3.75 



No. Price. 

119. Improved set of Jars 6.50 

120. Stand and Bells 5.00 

121. Ether Spoon 1.25 

122. Spiral Tube 4.00 

124. Discharger 3.50 

125. Gas Pistol 1.00 

126. Powder Bomb 2.00 

129. Dancing Balls 25 



Magnetics. 

140. Bar Magnet 1.00 

142. U Magnet and Wheel 3.75 

143. Needle and Stand 1.50 

147. Bunsen's Battery 4.50 

150. Powder Cup 1.75 

153. Electro Magnet 2.50 

154. Heliacal Ring 4.25 

156. Revolving Magnet 8.00 

157. Galvanometer 4.75 

159. Telegraph Model 9.00 

163. Double Helices 8.50 

164. Handles and Wires 2.00 



Acoustics. 

180. Sonometer 35.00 

183. Screw Press 7.50 

184. Vibrating Plate 3.50 

187. Diapason 11.00 

188. Violoncello Bow 2.00 

191. Organ Pipe 4.50 

194. Bell in Vacuum 3.50 



Optics. 
201. Prism. 

204. Multiplying Lens 

205. Convex and Concave Lenses. . 
208. Convex and Concave Mirrors. 

212. Model of the Eye 8.00 

216. Newton's Disk 75 



2.00 

.75 

3.00 

6.50 



Recapitulation. 

Mechanics 55.25 

Hydrostatics 36.50 

Pneumatics 71.00 

Heat 28.25 

Electricity 95.50 

Magnetism 51.50 

Acoustics 67.00 

Optics 21.00 



$426.00 



34 



SCHOOL APPARATUS, 



SET No. 3. 



Laws of Matter. 
No. Price. 

2. Lead Hemispheres 1.25 

3. Inertia Apparatus 1.75 

5. Capillary Tubes 1.50 

6. Capillary Plates 1.50 

7. Collision Balls 7.25 

9. Centre of Gravity 11.00 

11. Illustration of Pulleys 27.50 

13. Screw, Wedge, etc 7.50 

16. Lever, Balance, etc 12.50 

17. Central Forces 4.50 

18. Pendulum 3.50 

Hydrostatics. 

20. Equilibrium Tubes 4.25 

22. Cylinder and Plate 3.00 

23. Adhesion Plate 1.50 

24. Siphon. , 75 

25. Tantalus's Cup 2.50 

28. Set of Pumps 22.50 

29. Archimedes Principle 3.50 

31. Hydrometer 1.25 

299. Hydrometer Jar 1.25 

34. Hydraulic Press 12.50 

37. Hero's Fountain 8.00 

Pneumatics. 

41. Air Pump 45.00 

42. Receiver 1.25 

43. Receiver 5.50 

45. Sliding Rod 2.75 

46. Screw Plug 75 

47. Hand Glass 1.25 

48. Condenser 9.50 

49. Condensing Chamber 9.50 

51. Bolt Head 75 

52. Freezer 4.00 

53. Bacchus Illustration 3.75 

54. Magdeburg Hemispheres. . . 7.50 

55. Rubber Bag 2.25 

56. Weight and Buoyancy 12.00 

58. Barometer Tube 1.50 

259. Mercury 2.00 

63. Guinea and Feather Tube. . . 8.00 

64. Air Gun 1.25 

65. Revolving Jet 3.75 

66. Wood Cylinder 25 

68. Washers 25 

69. Oil 50 

Heat. 

70. Palm Glass 1.00 

73. Bar and Gauge 2.75 

74. Compound Bar 2.25 



No. Prioe. 

75. Fire Syringe 3.00 

76. Reflectors 12.50 

77. Wollaston's Engine 5.50 

78. Wire Gauze 75 

79. Specific Heat 1.75 

82. Ventilation 3.50 

S4. Thermometer for Liquids. . . 1 .25 

86. Conductometer 4.50 

87. Eolipile 3.50 

88. Pyrometer 7.50 

292. Spirit Lamp 1.00 

Electricity. 

99. Holtz Machine 45.00 

100. Cat's Skin 50 

101. Insulated Support 13.50 

102. Friction Cylinder 75 

103. Electroscope 1.25 

106. Tellurian 6.50 

110. Stool , 5.50 

114. Movable Coatings Jar 3.75 

116. Diamond Jar 3.00 

119. Set of Jars 0.50 

120. Stand and Bells 5.00 

121. Ether Spoon 1.25 

122. Spiral Tube 4.00 

124A. Jointed Discharger 5.25 

125. Gas Pistol 1.00 

126. Powder Bomb 2.00 

129. Pith Balls (2 dozen) 50 

130. Cascade 2.50 

132. Luminous Points 3.00 

Magnetics. 

140. Bar Magnet 1.00 

142. U Magnet and Wheel. . . . . 3.75 

143. Needle and Stand 1.50 

147. Bunsen's Battery 4.50 

150. Powder Cup 1.75 

151. Contracting Helix 5.50 

152. Decomposing Cell 5.25 

153. Electro Magnet 3.50 

154. Heliacal Ring 4.25 

155. Lifting Coil 4.00 

156. Revolving Magnet 8.00 

157. Galvanometer 4.75 

159. Telegraph Model 9.00 

163. Double Helices 8.50 

164. Handles and Wires 2.00 

Acoustics. 

180. Sonometer 35.00 

182. Toothed Wheel 7.50 

183. Screw Press 7.50 

184. Vibrating Plate 3.50 



SCHOOL APPARATUS. 



35 



No. 
185. 
187. 
188. 
191. 
192. 
194. 



202. 
203. 
204. 
206. 
208. 
212. 
214. 



Price. 

Brass Rod and Ball 3.75 

Diapason 11.00 

Violoncello Bow 2.00 

Organ Pipe 4.50 

Reed Pipe 4.75 

Bell in Vacuum 3.50 

Optics. 

Mounted Prism 0.00 

Achromatic Prism 7.50 

Multiplying Lens 75 

Set of Lenses fl.00 

Set of Mirrors 6.50 

Model of the Eye 8.00 

Revolving Disk Apparatus. . . 9.00 



No. Price. 

215. Set of Disks 2.50 

218. Zoetrope COO 

Recapitulation. 

Laws of Matter 79.75 

Hydrostatics 63.50 

Pneumatics 120.75 

Heat 50.75 

Electricity 110.75 

Magnetics 67.25 

Acoustics 83.00 

Optics 56.25 

$632.00 



The above sets have been compiled with the view to combine instruments for the 
illustration of as many and as varied principles as the limits of the amount of each 
will permit, to avoid duplications, and as far as possible to represent proportionately 
each department of physical science. 

Where the requirements of the Institution would be better subserved by giving 
greater prominence to particular branches, a selection may be made by taking the 
separate departments from different sets. 

It will be seen that some valuable instruments have not been included in either of 
the sets, but only those that are generally required; the purchaser can add such to 
his order, or make such other changes as he may desire. 

All the articles in this Catalogue are, in size and quality, such as will make them 
suitable for portions of a most extensive cabinet. Our large Catalogue contains many 
instruments, in all departments, omitted in this simply because they are beyond the 
requirements of our high schools generally. 



"We will send either of tlie above Sets, or any- selection 
made by taking Departments from either of the sets, free 
from charge of packing, and at our risk of loss or of 
"breakage, provided that no change is made in any sepa- 
rate department, and that the whole amount is not less 
than one hundred dollars. This would not prevent addi- 
tional articles of any kind from being sent therewith. 



E. S. RITCHIE & SONS, 

Manufactory, Brookline. Office, 150 Tremont Street, fronting the Common, 
BOSTON, MASS. 



Testimonials. 



Boston, Aug. 10, 1857. 
I take pleasure in bearing testimony to the great skill, faithfulness, and ingenuity 
of Mr. Eitchie, as a maker of Philosophical Instruments. Uniting an ample knowl- 
edge of scientific principles to large experience in the mechanical details of his pro- 
fession, his work commends itself not only to institutions seeking apparatus for lec- 
ture-room illustration, but to men of science pursuing original research. 

WILLIAM B. ROGERS. 



Amherst, June 5, 18G9. 
I have for many years been acquainted with Mr. E. S. Ritchie, as a designer and 
manufacturer of philosophical apparatus, and am prepared to speak in high terms of 
his intelligence and mechanical skill, as well as his courteous attention to those who 
apply to him for counsel or aid in his line of business. I am glad to look over the 
new catalogue of apparatus for schools, which Ritchie & Sons are just issuing, and to 
recommend it to the attention of all who wish to become purchasers. The improve- 
ments which they have made in many of the common philosophical instruments, have 
more than doubled their value. Teachers and experimenters may rely on the strict 
fidelity of the Messrs. Ritchie, in Regard to the quality and aduptedness of the articles 
which they furnish. 

E. S. SNELL, 
Prof, of Nat. Philosophy, Amherst College. 



East Hampton, June 5, 1869. 
Mr. E. S. Ritchie has made a large amount of philosophical apparatus for me, at 
different times, and it has given me great satisfaction. In simplicity of design, accu- 
racy of operation, and perfection of workmanship, it is not surpassed. His Patent 
Air Pump is a very great improvement upon anything of the kind before constructed. 
It easily makes a vacuum nearly as complete as can be obtained by the laborious pro- 
cess of the mercury pump. The exhibition of the electric light in the vacua produced 
by it is equal to that in the best Geissler tubes. 

MARSHALL HENSHAW, 

President Williston Seminary. 



From Mr. John P. Gassiot, Vice-President of the Poyal Society. 

London, March 7, 1859. 
Dear Sir : I have great pleasure in assuring you that the Induction Coil, which, 
through the introduction of my friend, Prof. William B. Rogers, you constructed for 
me, answers most admirably. With five of Grove's nitric acid battery cells I obtain 
eleven and a half inch sparks. The Vibrating Contact Breaker, which you subse- 
quently sent, has enabled me to repeat all the experiments with my Vacua Tubes, 
while the three divisions in your Coil affords facilities for varying the experiments in 
a manner that can be well appreciated by those who have worked with this apparatus. 

Believe me, dear sir, yours truly, 

JOHN P. GASSIOT. 
To Edward S. Ritchie, Boston, U. S. A. 



TESTIMONIALS. 37 

United States Military Academy, West Point, N. Y., June 4, 1869. 
The best portion of the apparatus in use in the Chemical Department at this institu- 
tion, has been made under the direction of Mr. E. S. Ritchie, of Boston. In all re- 
spects, everything that has been received from him, whether ordered in person or by- 
letter, gives complete satisfaction. His Electrical and Pneumatical Instruments are 
of unequalled excellence. 

I have found Mr. Ritchie to be not only an entirely reliable gentleman, but one 
whose scientific attainments make him a valuable adviser. 

H. L. KENDRICK, 
Prof. Chemistry, cfc, U. S. Military Academy. 



Cambridge, Sept. 10, 1852. 
This may certify that Mr. E. S. Ritchie is well known to us as a manufacturer of 
the best philosophical instruments used in academies and colleges. He is not content 
with supplying the usual apparatus found in all the catalogues, but he is ambitious to 
add to it new articles which illustrate fresh discoveries in science, or which excite a 
scientific curiosity. His integrity, his urbanity, and his skill all equally entitle him 
to the confidence of those who purchase or use philosophical apparatus. 

JOSEPH LOVERING. 
Hollis Prof, of Mathematics and Nat. Philosophy in Harvard College. 
JOSIAH P. COOKE, Jr., 
Erving Prof, of Chemistry and Mineralogy in Harvard College. 



Dartmouth College, Hanover, N. H., May 22, 1869. 
I take pleasure in bearing witness to the excellence of the Philosophical Apparatus 
manufactured by E. S. Ritchie & Sous. I have never found anything better in re- 
spect to accuracy of workmanship, and efficiency of operation. Their efforts to pro- 
mote science by being the first manufacturers in the country to construct the Induc- 
tion Coil, and the Holtz Electrical Machine, have deserved and obtained for them the 
regard of all American scientific men, and given them even a European reputation. 

C. A. YOUNG, 
Prof, of Nat. Philosophy and Astronomy. 



New York, Sept. 1, 1857. 
It is with great pleasure that I offer my testimony in favor of the excellent Philo- 
sophical Instruments constructed by Mr. E. S. Ritchie, of Boston. I have uniformly 
found them accurately and carefully made, durable and elegant. Mr. Ritchie seeks 
not alone to equal the best foreign instruments, but to surpass them, and to keep pace 
with the advancement of science. I have had repeated proofs of a characteristic pos- 
sessed by Mr. Ritchie, which I feel confident will be appreciated, viz., the sympathy 
and interest he manifests with the success of the experimenter, associated with a 
pride for his reputation, punctuality, and a determination to accomplish his aims. 

Respectfully submitted, 

R. OGDEN doremus, m. d., 

Prof. Chemistry New York Medical College, and College of Pharmacy. 



St. Louis, Mo., May 28, 1869. 
I am now using the Philosophical and Chemical Apparatus of E. S. Ritchie & Sons. 
Everything which I have seen of their manufacture has borne marks of mechanical 
skill, scientific knowledge, and the honesty which gives skill and knowledge their 
best results. 

C. S. PENNELL, 
Prin. of Mary Inst., a department of Washington University. 



38 



TESTIMONIALS 



University of Pennsylvania, Philadelphia, July 10, 1857. 
Having used with much satisfaction a variety of apparatus manufactured by Mr. 
E. S. Ritchie, I take great pleasure in bearing testimony to his ingenuity and scien- 
tific skill as a Philosophical Instrument maker. 

R. E. ROGERS, 
Prof, of Chemistry in the University of Pennsylvania. 



Andover, March 22, 1869. 
From time to time during the last ten years, I have had occasion to purchase appa- 
ratus of Mr. Ritchie, and have found every article satisfactory. Mr. Ritchie is pos- 
sessed of rare skill and ingenuity, and evidently takes pride in having every piece of 
apparatus in perfect order before it leaves his hands. 

WM. G. GOLDSMITH, 
Principal Punchard Free School. 



Yale College Laboratory, June 17, 1859. 

Scientific men in the United States, and teachers generally, are under many obliga- 
tions to Mr. Ritchie, not only for the general superiority of his apparatus, but espe- 
cially for his enlightened enterprise in undertaking many things for which we have 
before depended on Europe. 

I have found Mr. Ritchie ready at all times to undertake commissions out of the 
routine of his business, relying for his reward upon the reputation growing out of 
such a course. 

All the apparatus which I have had from Mr. Ritchie has been exceedingly well 
made, and has given me entire satisfaction. His stock of Physical and Chemical Ap- 
paratus is excellent. The pieces are well made, in good taste, and of reasonable price. 

B. SILLIMAN, Jr. 



Extract of Letter from Prof. Forbes, of the University of Edinburgh. 

Edinburgh, 16 July, 1858. 
My Dear Sir : . . . I have been highly pleased with the instrument. I have shown 
it in action to many scientific men, including Sir David Brewster. 

I remain, dear sir, yours faithfully, 

JAMES D. FORBES. 



Office of Sup't Public Sthools, Chicago, Feb. 15, 1859. 
The Board of Education of this city has recently purchased of E. S. Ritchie, of 
Boston, one thousand dollars' worth of apparatus, for the use of the Chicago High 
School. In thoroughness of workmanship and elegance of finish, it is unsurpassed 
by any apparatus that has fallen under my observation. Its performance is in the 
highest degree satisfactory. W. H. WELLS, 

Superintendent Public Schools. 



New England National Bank, Boston, June 4, 1869. 
Messrs. Edward S. Ritchie & Sons. 

Gentlemen : In my opinion, your house may be relied on for faithfully performing 
all its promises and obligations; and this I declare, not only from a sufficient knowl- 
edge of it, but also from an intimate acquaintance with its members of longer stand- 
ing than the establishment. 

With esteem, yours truly, 

THOMAS LAMB, President. 



RITCHIE'S 



CATALOGUE 



OF 



SCHOOL APPARATUS 




E. S. RITCHIE & SOINrS, 

No. 150 TftEMONT STREET, 

BOSTON. 

18T3. 



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